When the history of Syria's catastrophic civil war comes to be written, 30 June 2012 will surely be recognised as the only true moment of hope. On that day in Geneva the five permanent members of the UN security council united behind a communique calling for a transition to a democratic system in Syria and the formation of a government of national unity in which opposition leaders and members of the current government would share power.

They called for a firm timetable for elections in a fair environment. And, with an eye on the chaos that followed the US-imposed scheme of de-Ba'athification in Iraq, said the continuity of government institutions and qualified staff in Syria's public services must be preserved. This included the military and security forces – though they must in future adhere to human rights standards.

They also called on the Syrian government and opposition groups to re-commit to a ceasefire. Sensible, detailed and constructive, the communique was also remarkable for what it did not contain. Although the call for a government of national unity meant Syria's authoritarian regime should be dismantled, the security council's permanent members did not mention the usual cliche of "regime change", which over-personalises complex issues by focusing on the removal of a single towering personality. There was no specific demand for Bashar al-Assad to resign, let alone as the precondition for negotiations between the government and its opponents, as western states and most Syrian opposition groups previously insisted.

In short, the communique appeared to move the US, Britain and France, as well as Turkey and Qatar, which also attended the Geneva meeting, to an even-handed stance at last. It marked Kofi Annan's finest hour as the UN and Arab League's special envoy.

A few days later, Russia circulated a draft resolution at the UN in New York to endorse the new approach. It urged member-states to work in the co-operative spirit of the Geneva text, extend the UN monitors' team in Syria and press for a ceasefire. Then came the spanner. Britain, France and the US proposed a rival resolution with the one-sided elements that provoked earlier Russian and Chinese vetoes – punishment of Assad if he did not comply, threats of new sanctions, no word of pressure on the opposition and veiled hints of eventual military force by referring to chapter seven of the UN charter.

The resolution was a disaster, and it is no wonder that in explaining his resignation (in a Financial Times article on Friday) Annan highlighted the security council's failure to endorse the Geneva recommendations. Annan remains too much of a diplomat to take sides openly but his disappointment with the big western states for their "finger-pointing and name-calling" of Russia and China over Syria is clear.

His frustration is shared by the new powers on the international stage that are increasingly angry with the domineering western consensus on many issues. When the UN general assembly debated a Saudi resolution last week that followed the west in calling for sanctions and Assad's departure, Brazil, India and South Africa all objected. In the west it is easy to pillory Russia for rejecting internationally imposed regime change by saying Vladimir Putin fears a "colour revolution" in Russia (even though there is no such prospect). China's democratic credentials can be sneered at. But when the three other Brics, which hold fair, orderly, and regular elections, object to the western line on Syria, it is time to take note. Indeed, the west did adjust. It got the Saudis to water down the draft lest it receive less than half the world's votes.

The retreat was only tactical. The Obama administration promptly announced it is "accelerating" its support to Syria's rebels by giving them intelligence and satellite data on troop movements. Annan's disappointment must be massive. Until he started work in February, the military pattern in Syria had been consistent for several months – occasional forays by rebels into urban areas followed by excessive reaction by government troops, with artillery, snipers, and mass arrests.

Since then, apart from a few days of relative quiet in April when a ceasefire partially held, Syria has seen a huge influx of arms to the rebels, growing involvement by foreign special forces, and the infiltration of al-Qaida jihadis and other Salafists. What began as a peaceful uprising and then became local self-defence has been hijacked. Under Saudi, Qatari and US leadership, and with British, French and Israeli approval, it has turned into an anti-Iranian proxy war.

This does not mean the democratic aspirations of Syria's original protesters should be abandoned, or that the Syrian government should not start to implement the Geneva principles for transition that Annan briefly persuaded the big powers to accept. The outlook is too desperate. As tens of thousands flee their homes, and the destruction of Aleppo – and perhaps soon of Damascus – looms ever closer, a ceasefire and political compromise have never been more urgent.